plot multiple datasets with gnuplot script from stdin

Question

I am trying to plot some data with gnuplot. I want to use a static script.gp file and feed it from stdin with my data. I also have multiple datasets that I need to pass to the script.

script.gp:

set term jpeg
set encoding utf8
plot '<cat' index 0 with lines, plot '' index 1 with lines

data:

command:

cat data | gnuplot script.gp

This doesn't work, since I'm guessing it tries to reread from stdin. Is there a way I can do this, or do I have to use temporary files to store my data?

if your data is already in a file, why don't you just plot the file? If the data is coming from a command, why don't you ask gnuplot to plot the output of the command? e.g. plot '< for i in {1..50}; do echo "$RANDOM"; done' w l maybe help special can give some hint for your case — bibi
– bibi, Commented Jan 25, 2016 at 15:11
Thanks for the reply. The data is not already in a file, it's generated on the fly (by a php script). My thought was to have a gnuplot script, version controlled and all, describing the format of the plots I want, and call that script with different datasets in order to generate the plots. — Alexis Panagiotopoulos
– Alexis Panagiotopoulos, Commented Jan 26, 2016 at 13:51

Alexis Panagiotopoulos · Accepted Answer · 2018-12-17 19:45:13Z

2

The solution I 've found so far has plenty of drawbacks, however it kind of does the job:
Use 'gnuplot -e' and cat the script file into the command:

cat data | gnuplot -e "$(cat script.gp)"

change script.gp using ; at the end of every line, remove all comments and change the plot command using '-' instead of '<cat' and removing index:

set term jpeg;
set encoding utf8;
plot '-' with lines, '-' with lines

change the data format, seperating each dataset with a line with e:

edited Dec 17, 2018 at 19:45

answered Jan 25, 2016 at 13:13

Alexis Panagiotopoulos

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user545424 Over a year ago

This works great! Although I think in your second code block it should be plot '-' with lines, '-' with lines.

bibi · Accepted Answer · 2016-01-26 14:38:33Z

0

I would suggest to use the special file '<' which allows you to call the php script and you can have your gnuplot file plot.gp:

set term jpeg;
set encoding utf8;
set output file_out

my_cmd1=sprintf('< my_script %s', my_file1)
my_cmd2=sprintf('< my_script %s', my_file2)
plot my_cmd1 with lines, my_cmd2 with lines

and you call in a shell with:

gnuplot -e 'my_file1="input1.txt"; my_file2="input2.txt"; file_out="my_out.jpg"' plot.gp

answered Jan 26, 2016 at 14:38

bibi

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